Abstract: A processing apparatus with a movable processing tool, which includes a position detecting sensor for detecting a rotary position of a to-be-processed object held by a holding member set to a rotary main shaft, a deflection detecting sensor for detecting an amount of rotational deflection of a processing reference surface of the object, a waveform shaping device for shaping an output signal from the deflection detecting sensor into a waveform approximate to a sine curve, an operational device for operating a positional correction amount for a processing tool at a processing point of the object on a basis of an output signal of the waveform shaping device synchronously with rotation of the rotary main shaft, an output device for outputting the positional correction amount for every rotary position and every processing point based on an output signal from the operational device, a fine adjustment mechanism for minutely driving the processing tool based on an output signal from the output device, and an NC table

Abstract: A hydrodynamic gas bearing includes a cantilevered shaft having a free end, a fixed end, and a communicating hole for communicating with a passage formed at an end surface of the free end of the shaft. A cover member is rotatably arranged around the shaft to cover a periphery of the shaft. One of an inner surface of the cover member which faces the fixed end of the shaft and an outer surface of the fixed end of the shaft having a herringbone-configured hydrodynamic pressure generating grooves for preventing gas from being fed from a fixed end side to a free end side of the shaft. One of the inner surface of the cover member which faces the free end of the shaft and an outer surface of the free end of the shaft has helical-configured hydrodynamic pressure generating grooves for feeding gas from the free end side to the fixed end side of the shaft.

Abstract: A hydrodynamic gas bearing includes a cantilevered shaft having a free end, a fixed end, and a communicating hole for communicating with a passage formed at an end surface of the free end of the shaft. A cover member is rotatably arranged around the shaft to cover a periphery of the shaft. One of an inner surface of the cover member which faces the fixed end of the shaft and an outer surface of the fixed end of the shaft has herringbone-configured hydrodynamic pressure generating grooves for preventing gas from being fed from a fixed end side to a free end side of the shaft. One of the inner surface of the cover member which faces the free end of the shaft and an outer surface of the free end of the shaft has helical-configured hydrodynamic pressure generating grooves for feeding gas from the free end side to the fixed end side of the shaft.